Autofocus systems automatically adjust the distance between a lens element and an image sensor to keep objects in focus. Many of these systems determine the best focus based on high frequency content within the image being focused. For example, a lens position that maximizes the high frequency content may represent an image with the best contrast ratio, and thus the best focus. However, existing autofocus systems may lose focus when an object moves relative to the camera. Therefore, there is a need for systems and methods that continuously and automatically maintain focus on moving objects.